Real Life 'Predator' Armor? Researchers Make Breakthrough in Quest for Invisibility Cloaking

Despite scientists claiming that a Harry Potter-style invisibility cloak is pretty much impossible, researchers have created near-invisible stealth drones and metamaterials that can even make a jet fighter almost impossible to spot. Now, a new study published in Optica claims to have made a major leap toward making functional invisibility a reality: "Our work represents a breakthrough in the quest for invisibility cloaking," says José Azaña, one of the researchers involved in the study. "We have made a target object fully invisible to observation under realistic broadband illumination by propagating the illumination wave through the object with no detectable distortion, exactly as if the object and cloak were not present."

The method Azaña and the team used is called "spectral cloaking," and is fundamentally different from the more common "temporal cloaking:" temporal cloaking tries to divert light waves around an object, which creates tell-tale distortions that can tip off observers that something is being hidden, while spectral cloaking rebalances energy among the different bands of color within a lightwave, effectively muting the colors of the object its cloaking and making them invisible. In the study, the cloaking device was used to disguise the presence of a colored object that allowed light to pass through it. According to Phys.org:

To do this, the cloaking device first shifts the colors toward regions of the spectrum that will not be affected by propagation through the object. For example, if the object reflects green light, then light in the green portion of the spectrum might be shifted to blue so that there would be no green light for it to reflect. Then, once the wave has cleared the object, the cloaking device reverses the shift, reconstructing the wave in its original state.

Though this type of invisibility is currently being proposed for use in protecting data transmitted through fiber optics, it may be useful in making 3-D objects invisible as well.